JP3139114B2 - Method for hydrorefining naphthalene - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for hydrorefining naphthalene for producing purified naphthalene by removing sulfur and nitrogen compounds contained in crude naphthalene by hydrogenation.

[0002]

BACKGROUND OF THE INVENTION Crude naphthalene, especially 95% naphthalene obtained by fractionation of coal tar, usually contains several thousand ppm of sulfur compounds and several hundred ppm of nitrogen compounds as impurities. As methods for obtaining purified naphthalene by removing these, (1) a method of washing with an acid (literature: Tar Kogyo Handbook), (2) a method of crystallization (Japanese Patent Publication No. 47-47023, Tar Kogyo Handbook, etc.), ( 3) White clay treatment (Japanese Patent Publication No. 47-47022) and the like are known and are industrially practiced. However, these methods have many problems, such as high utility and other refining costs, large amounts of wastewater generated, and insufficient nitrogen and sulfur removal rates. Combination methods and the like have been published, but such complicated processes are increasing the cost of purification. Under such circumstances, there is a demand for a naphthalene purification method that is simpler, less expensive, less polluting and can remove nitrogen and sulfur up to 10 ppm or less.

[0003] On the other hand, as with hydrorefining of benzenes and petroleum products, many studies have been made on the hydrorefining of naphthalene since ancient times. However, since the naphthalene ring is much more active than the benzene ring, a nuclear hydrogenation reaction takes place in parallel with desulfurization or denitrification during naphthalene hydrorefining, or rather in preference to these objective reactions.
Since tetralin and decalin are by-produced, and further, alkylbenzenes are produced as a by-product of their decomposition, the yield of purified naphthalene is significantly reduced. That is, in order for the hydrodesulfurization / denitrification reaction of petroleum products to proceed at a substantially effective reaction rate, a reaction temperature higher than a specific temperature determined by the catalyst to be used is necessary. As the reaction rate rises, the reaction rate also reaches the reaction arrival rate (desulfurization / denitrification rate)
In general, in the hydrorefining of crude naphthalene, the nuclear hydrogenation of the naphthalene ring proceeds concurrently, and this reaction also has the same reaction temperature and temperature as the hydrodesulfurization and denitrification reactions. Because of the pressure dependence, it is extremely difficult to completely suppress nuclear hydrogenation and completely advance only desulfurization and denitrification, and there is a problem that the yield of purified naphthalene is inevitably significantly reduced. Therefore, when a hydrogenation treatment is used for the purification of crude naphthalene, a method in which a mild hydrogenation treatment is combined with a chemical washing treatment such as acid and / or alkali washing (JP-A-61-57527), A method of performing a pressing treatment or a clay treatment (Japanese Patent Application Laid-Open No. 54-14442)
49, JP-B-60-58733, 62-2567) and the like. On the other hand, a technology for producing tetralin by nuclear hydrogenation of naphthalene (Japanese Patent Publication Nos. 50-38100, 56-
1293) is also known, but in this case, 90% or more of the raw material naphthalene is nuclei hydrogenated and taken out as tetralin.

[0004] In Japan, purified naphthalene, which is currently industrially produced on a large scale, is produced by a process centered on crystallization, so that the purity of naphthalene is 99% or more, but the residual sulfur is less than 99%. It also contains about 100 to 1000 ppm.
Therefore, although it can be used for applications such as insect repellents, phthalic anhydride, and β-naphthol production, when used as an alkylation reaction raw material such as isopropyl naphthalene production, it deteriorates the alkylation catalyst. However, there is still a problem. In order to suppress the deterioration of the alkylation catalyst, it is usually necessary to reduce the amount of nitrogen and sulfur to 10 ppm or less. Therefore, in order to obtain highly purified naphthalene satisfying this criterion, at present, it is necessary to combine various treatment methods as described above.

[0005]

DISCLOSURE OF THE INVENTION The present invention relates to a hydrorefining of crude naphthalene, particularly tar-based crude naphthalene having a large coexistence amount of a sulfur compound and a nitrogen compound, wherein the residual amount of the nitrogen compound and the sulfur compound is 10 ppm or less, and An object of the present invention is to provide a method for giving an improved yield of purified naphthalene.

[0006]

Means for Solving the Problems In order to solve the above problems, the present inventors have made various studies on the catalyst used and the hydrogenation reaction conditions, and as a result, have completed the present invention. That is, according to the present invention, a crude oil obtained by mixing crude naphthalene with tetralin in a ratio of 0.1 to 0.8 part by weight with respect to 1 part by weight of naphthalene contained in the crude naphthalene is used as a hydrodesulfurization catalyst. A method for hydropurifying naphthalene, characterized by reacting with hydrogen under the reaction conditions of 350 ° C. to 420 ° C. and a hydrogen partial pressure of 5 to 40 kg / cm ² in the presence.

The hydrodesulfurization catalyst used in the present invention is a desulfurization catalyst.
What is necessary is just to have a denitrification activity, and conventionally well-known various things are used. Generally, those containing at least one metal selected from cobalt, molybdenum and nickel are preferably used. As the carrier for supporting these metals, conventionally known carriers such as alumina, silica, zirconia, and magnesia are used. The preferred support is alumina. The catalyst which is particularly preferably used in the present invention comprises 11 to 30% by weight, preferably 17 to 2% by weight of cobalt and molybdenum as oxides.
It contains 0% by weight. If the catalyst composition deviates from this range, it becomes difficult to carry out denitrification and desulfurization reactions while suppressing nuclear hydrogenation of naphthalene. Further, the use ratio of cobalt and molybdenum is 0.0% by weight of CoO / MoO _3.
It is good to be 5 to 0.7, preferably 0.25 to 0.28.

The catalyst used in the present invention has a specific surface area of 200 to 400 m ² / g, preferably 23
0-300 m ² / g, pore volume 0.37-0.57 ml
/ G, preferably 0.45 to 0.50 ml / g, an average pore diameter of 55 to 90 °, preferably 65 to 75 °, and 50% or more, preferably 60% or more of all the pores have a pore diameter of 55 to 90 °. And a pore size of 9
0% or less of the pores are less than 15% of the total pores, preferably 1%.
It has a sharp pore distribution of 0% or less. If the specific surface area is less than 200 m ² / g, the activity is low, while if it exceeds 400 m ² / g, coking tends to occur. When the pore volume exceeds 0.57 ml / g, the denitrification / desulfurization activity deteriorates. If the average pore diameter is too large, hydrogenation of the naphthalene nucleus and hydrogenolysis of the tetralin nucleus become active, and coking formation becomes remarkable. On the other hand, if the average pore diameter is too small, it becomes difficult to infiltrate molecules containing sulfur and nitrogen, so that the rate of occurrence of desulfurization reaction and denitrification reaction decreases, and effective hydrorefining cannot be performed. Such a catalyst can be advantageously used as a hydrorefining catalyst for crude naphthalene as well as crude naphthalene and tetralin.

In the physical properties of the catalyst described in the present specification, the surface area indicates the BET surface area determined from the amount of nitrogen adsorbed at the nitrogen boiling point, and the pore volume is determined by the nitrogen adsorption method. The pore distribution was measured by the mercury intrusion method, and was measured by Carboelver Porosimeter 2000.
Was used.

[0010] The method of the present invention is characterized in that the crude naphthalene is added in an amount of 0.1 to 1 part by weight of naphthalene in the crude naphthalene.
A feedstock obtained by mixing 0.8 parts by weight, preferably 0.2 to 0.4 parts by weight of tetralin, is heated in the presence of the hydrodesulfurization catalyst at a temperature of 350 to 420 ° C., preferably 370 to 40 ° C.
0 ° C., hydrogen partial pressure: 5 to 40 kg / cm ² , preferably 10
This is a method of reacting with hydrogen under a reaction condition of ３０30 kg / cm ² . When the crude naphthalene mixed with tetralin is hydrorefined under the above-mentioned reaction conditions, the reaction temperature and hydrogen partial pressure are selected so as to correspond to the thermal equilibrium conditions of hydrogen-naphthalene-tetralin, whereby the nuclear hydrogenation of naphthalene can be performed. Can be suppressed, and each loss of naphthalene and hydrogen can be prevented. That is, when the crude naphthalene is hydrorefined in the presence of tetralin, there is a condition that a thermal equilibrium is established between naphthalene, tetralin and hydrogen present in the reaction system. Under these thermal equilibrium conditions, when it is desired to maintain the weight ratio of naphthalene and tetralin within a certain range, thermal equilibrium can be established by adjusting the hydrogen partial pressure and the reaction temperature in accordance with the weight ratio. Therefore, when a certain amount of tetralin is added to the raw crude naphthalene, the thermal equilibrium corresponding to the weight ratio of naphthalene and tetralin can be established by adjusting the hydrogen partial pressure and the temperature. When the crude naphthalene is hydrorefined under these thermal equilibrium conditions, the crude naphthalene can be hydrorefined while the nuclear hydrogenation ratio of naphthalene in the crude naphthalene is kept at substantially zero%. On the other hand, the nitrogen content and the sulfur content in the crude naphthalene are sequentially decomposed under the above reaction conditions, and are removed as gas components. Therefore, in the present invention, nitrogen and sulfur can be removed to several ppm without consequent loss of naphthalene. In order to quickly establish the thermal equilibrium condition, the reaction temperature is a major factor. When the reaction temperature is low, the time to reach the thermal equilibrium condition becomes longer, and when the reaction temperature is high, the time becomes shorter. And, as can be seen from FIG. 1, since the reaction temperature is high and the concentration of naphthalene in the equilibrium composition is high, loss of naphthalene can be prevented. From this point, it is advantageous to use a reaction temperature of 330 ° C. or higher, especially 350 ° C. or higher.

In FIG. 1, a solution having a composition of naphthalene: tetralin = 7: 3 (weight ratio) in the presence of the catalyst (NKK-1) shown in Table 1 is hydrogenated at a rate of LHSV: 0.4 hr ^-1 . 4 shows the relationship between the concentration of residual naphthalene in hydrogenated oil and the reaction temperature when refined. 330 ° C with fast hydrogenation and dehydrogenation rates
Above, an equilibrium is obtained, but at a temperature lower than 330 ° C., the reaction occurs in a non-equilibrium state. FIG. 1 also clearly shows that the equilibrium composition fluctuates due to the difference in pressure. As described above, the equilibrium composition is determined by temperature and pressure, and the equilibrium composition of naphthalene 7: tetralin 3 is 15 kg / c in total pressure shown in FIG.
The reaction conditions are not limited to m ² and a temperature of 390 ° C., but can be obtained under other reaction conditions, for example, a condition of a total pressure of 20 kg / cm ² and a temperature of 401 ° C. And under such equilibrium conditions,
It is contained in the raw material liquid. Hydrorefining proceeds smoothly without causing nuclear hydrogenation of naphthalene and, therefore, without causing loss of naphthalene or hydrogen. Reaction temperature is 420 ° C
The temperature is preferably defined as follows. If the temperature exceeds 420 ° C., thermal decomposition of tetralin and formation of coke become remarkable, which is not preferable. The hydrogen partial pressure is generally 40 kg / cm
^If it is higher than ² , the reaction temperature needs to be significantly increased in order to obtain a hydrogenated oil having a high naphthalene content, which is not preferable. The gas / liquid ratio (Nm ³ / kl) for hydrorefining is 100 to 2000,
Preferably it is in the range of 300 to 1,000. It is practical to control the reaction conditions in the present invention so that the composition of the hydrogenated oil obtained is within ± 10% of the equilibrium composition at that temperature. When the hydropurification of the crude naphthalene is performed by adding tetralin to the crude naphthalene as described above, the tetralin contained therein is separated from the obtained hydrogenated oil by a separation method such as a distillation treatment, and this is again subjected to crude naphthalene. It is preferable to use the tetralin as an addition tetraline in circulation.

The crude naphthalene used in the present invention can be petroleum or coal (coal tar).
The naphthalene concentration in the crude naphthalene is at least 90% by weight, usually in the range of 95 to 97% by weight. The refined naphthalene produced according to the present invention has a high purity of 10 ppm or less in the content of sulfur and nitrogen. If it is desired to further improve the purity, the crystallization treatment or the clay treatment is performed after the hydrogenation purification. Alternatively, a purification treatment such as a distillation treatment may be performed.

[0013]

According to the present invention, pure white purified naphthalene from which sulfur and nitrogen have been removed to 10 ppm or less, respectively, can be obtained in good yield while suppressing each loss of naphthalene and hydrogen.

[0014]

EXAMPLES Hereinafter, the present invention will be described specifically with reference to typical examples and comparative examples, but the present invention is not limited to these examples. The examples and comparative examples of the present invention are composed of a stainless steel external electric heating type reactor having an inner diameter of 19.4 mm and a length of 3205 mm, a two-column gas-liquid separator, a plunger pump, a hydrogen cylinder, and a pressure regulating valve. This was performed using a continuous hydrogenation apparatus. Further, the reactor was filled with 200 ml of hydrogenation catalyst corresponding to each experiment so as to be distributed at the center of the electric furnace, and further, ceramic balls having a diameter of 1/16 inch were filled above and below the catalyst layer. The reaction temperature at the catalyst charging site was measured with five thermocouples installed in a pipe having an outer diameter of 8 mm passed through the center of the reactor, and the temperature was adjusted with an external heater divided into five. Hydrogen was prepared by diluting a cylinder packed with nitrogen and using it as a 90% concentration hydrogen gas. Feed oil and hydrogen were supplied in a downward flow system. Preliminary sulfurization known as a method for increasing the activity of the catalyst is performed by pressurizing the catalyst layer with 3% hydrogen sulfide (the remainder is nitrogen) to 15 kg / cm ² ,
The test was performed by maintaining the temperature at 0 ° C. for 3 hours. After the preliminary sulfurization, the temperature was once lowered to 200 ° C. and wetting was performed. Table 1 shows the characteristics of the catalyst used. The raw material crude naphthalene and hydrogenated oil were analyzed for composition by gas chromatography (GC16A, DB-W manufactured by Shimadzu Corporation).
AX column 60m, helium carrier gas pressure 3Kg / c
m ² , the temperature was raised from 100 ° C. to 220 ° C. at a rate of 2 ° C./min), and the analysis of nitrogen and sulfur was performed using a Doman trace NS analyzer. G / L described in Examples and Comparative Examples indicates the ratio between the supplied gas and the liquid. The gas was calculated using Nm ³ , and the liquid was calculated using the capacity (kl) at the supply temperature. . XP described in Examples
S is an X-ray photoelectron spectroscopy, also called ESCA, for measuring the fine structure and surface composition of the surface.
EPMA is an abbreviation of X-ray microanalysis, and is used for microanalysis of surface and analysis of microstructure, like XPS.

[0015]

[Table 1]

Example 1 As crude naphthalene, 96.4 wt% of naphthalene, 0.6 wt% of ethylbenzene, and sulfur content (S) of 5700 pp
m, a coal tar-derived material having a component composition of 655 ppm of nitrogen (N) was used. The crude naphthalene supply oil (A) was used as a crude oil, and this was used as a catalyst (NKK-1). As shown in Table 2, a hydrogen partial pressure of 13.5 kg / cm ² , L
Hydrogenation was performed under the conditions of HSV = 0.4, G / L = 1000, and temperature of 389 ° C. (Experiment No. 1). The composition of the hydrogenated oil after the reaction was approximately naphthalene 7 to tetralin 3. The residual N and S were very low, 1 ppm. The hydrogenated oil is subjected to distillation (100 theoretical plates, packed MacMahon batch distillation tower, operating at a top pressure of 50 torr and a reflux ratio of 10) to recover tetralin. The tetralin is mixed with crude naphthalene to form naphthalene 7. On the other hand, it was prepared to be tetralin 3 [supply oil (B)]. This supply oil (B)
Is hydrogenated under the same conditions as Experiment No. 1 (Experiment No. 1).
2) After the reaction, the composition of the hydrogenated oil was also tetralin 3 with respect to naphthalene 7, and the residual N and S were 1 ppm.

Example 2 0.39 parts by weight of tetralin containing about 0.5 wt% of decalin was mixed with 1 part by weight of the crude naphthalene,
A supply oil (C) having a component composition shown in Table 2 was prepared, and this was used as a catalyst (NKK-1) using a hydrogen partial pressure of 18 kg / cm ² , L
Hydrogenation was performed under the conditions of HSV = 0.2, G / L = 1000, and temperature of 401 ° C. (Experiment No. 3). The composition after the reaction was approximately naphthalene 7 to tetralin 3. Remaining N, S
Was very low, 1-2 ppm.

Example 3 The same feed oil (C) as in Example 2 was used, and this was used as a catalyst (NK).
K-1), hydrogen partial pressure 13.5 Kg / cm ² , LH
Hydrogenation was performed under the conditions of SV = 0.4, G / L = 1000, and temperature of 410 ° C. (Experiment No. 4). The equilibrium of the hydrogenated oil after the reaction was shifted to the naphthalene-rich side due to the high temperature, and as a result, a reverse reaction from tetralin to naphthalene occurred, and the amount increased more than the amount of naphthalene in the feed oil.

Example 4 A feed oil (D) prepared in advance to naphthalene 3: tetralin 7 was used, and this was used as a catalyst (NKK-1) at a partial pressure of hydrogen of 13.5 kg / cm ² , LHSV = 0.4, G /
Hydrogenation was performed under the conditions of L = 1000 and a temperature of 389 ° C. (Experiment No. 5). The composition of the hydrogenated oil after the reaction is approximately naphthalene 7
Showed an equilibrium composition with tetralin 3. The residual N and S were very low, 0 to 1 ppm.

Comparative Example 1 The same feed oil (C) as in Example 2 was used, and this was used as a catalyst (NK).
K-1), hydrogen partial pressure 90 kg / cm ² , LHSV
= 0.4, G / L = 1000, temperature 390 ° C (hydrogenation No. 6), 87% of decalin was produced.

Comparative Example 2 An experiment was conducted in the same manner as in Example 3 except that the supply oil (A) (crude naphthalene) was used (Experiment No. 7). In this case, coking occurred at the inlet of the reactor on the fifth day from the start of operation, and thus the reactor was shut down.

Example 5 Hydrogen partial pressure 13.5 kg / cm ² , LHSV = 0.4, G
/ L = 380, temperature 390 ° C., the catalyst (NKK-
1) Life test at high temperature was conducted (Experiment No.
8). Table 4 shows the results. No change in hydrogenated oil composition was observed even after exceeding 1000 hours, and no deterioration or coking of the catalyst was observed in the XPS measurement or EPMA test of the catalyst after the experiment.

[0023]

[Table 2]

[0024]

[Table 3]

[0025]

[Table 4]

Example 6 In Example 1, NKK-2 shown in Table 1 was used as a catalyst.
The experiment was performed in the same manner except that was used. Also in this case, the composition of the hydrogenated oil obtained is the ratio of tetralin 3 to naphthalene 7 and the residual N and S are very low and 1 pp
m or less.

[Brief description of the drawings]

FIG. 1 shows the relationship between the concentration of residual naphthalene in hydrogenated oil and the reaction temperature when crude naphthalene is hydrorefined in the presence of tetralin.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Takuro Iwama 1-1-2 Marunouchi, Chiyoda-ku, Tokyo Nippon Kokan Co., Ltd. (72) Inventor Hidetoshi Morotomi 1-1-2 Marunouchi, Chiyoda-ku, Tokyo Nippon Kokan (56) References JP-A-3-74336 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C07C 7/163 C07C 15/24

Claims (5)

(57) [Claims] 1. Crude naphthalene and tetralin are added in an amount of 0.1 to 1 part by weight of naphthalene contained in said crude naphthalene.
A feed oil mixed at a ratio of 0.8 parts by weight was heated at 350 ° C. to 420 ° C. and a hydrogen partial pressure of 5 to 4 in the presence of a hydrodesulfurization catalyst.
A method for hydropurifying naphthalene, comprising reacting with hydrogen under a reaction condition of 0 kg / cm ² . 2. The method according to claim 1, wherein the reaction conditions are hydrogen-naphthalene-tetralin thermal equilibrium conditions. 3. The method according to claim 1, wherein the hydrorefined oil obtained by the method according to claim 1 or 2 is subjected to a distillation treatment to separate tetralin, and the tetralin is mixed with crude naphthalene. . 4. The method according to claim 1, wherein the hydrodesulfurization catalyst contains at least one metal selected from cobalt, molybdenum and nickel. 5. The hydrodesulfurization catalyst has a specific surface area of 200-4.
00 m ² / g, pore volume 0.37-0.57 ml / g,
It has an average pore diameter of 55 to 90 °, 50% or more of all the pores are distributed in the range of 55 to 90 °, and
A cobalt-molybdenum-alumina catalyst having a sharp pore distribution in which pores exceeding 0 ° are 15% or less of all pores and containing a total of 11 to 30% by weight of cobalt and molybdenum as oxides. Any one of the methods 1 to 4.